The various components in a prefabricated housing unit are often assembled in various locations and then shipped to the prefabricated housing manufacturer for installation into the housing unit. The housing manufacturer generally assembles these components in assembly line fashion. As with any product manufactured on an assembly line, time and ease of construction are paramount considerations.
The installed components in the construction of a prefabricated housing unit include the doors and the door frames. The door or frame manufacturer generally will construct the frame, hang the doors on the frame, and then the ship the door frame assembly to the prefabricated housing manufacturer for installation therein.
An example of current door frame assembly design is shown in FIG. 1. In essence, the construction of this prefabricated door frame assembly 10 starts with the assembly of a wooden frame 20. An exterior aluminum frame 30 with one or more hinges 35 and a door stop 37 is attached to the wooden frame 20 and an aluminum screen door 40 is then attached to the hinges 35. One or more entry door hinges 50 and an entry door stop 55 are attached to the opposite side of the wooden frame 20. A steel entry door 60 is then attached to the entry door hinges 50. Weather stripping 65 is also applied. The unit 10 is then shipped to a housing manufacturer. The manufacturer slides and fastens the door frame assembly 10 into place in the prefabricated unit.
Although this method provides a door and door frame that can be easily installed into a prefabricated housing unit, there are drawbacks in terms of strength, security, and costs. The housing unit is only as strong and secure as the wooden frame upon which the doors are hung. Further, the method of construction for the frame manufacturer is expensive and time consuming given the number of parts involved. Several laborers are required to construct this type of door frame assembly.
Although it is known in the art of residential and commercial construction to use steel door frames for increased strength and security, such frames have not been used in the prefabricated housing industry because of difficulties in installation. These frames generally comprise several discrete components that are assembled at the construction site. For example, the assignee of the present application manufactures and sells a steel frame under the trademark "Rediframe" brand wall system. This product envelopes and is attached to the surrounding wall. As is shown in FIG. 2, the door frame assembly 70 comprises a header frame 75 and two side frames 80. Each frame member 75, 80 of the door frame assembly 70 surrounds the wall 86 and is held in place by a plurality of fasteners 90 which penetrate wall board 85 and engage the wall framing such as steel stud 95. The door frame assembly 70 is thus secured to the wall framing, such as steel stud 95, positioned behind the wall board 85. The doors are then hung after the frame unit 70 is in place in the wall 86.
Although a steel door frame would provide additional security, this type of construction is not suited for the prefabricated housing industry because of the time involved in attaching each of the respective frame members to the wall and then mounting the doors. In other words, this type of door frame is not appropriate for the prefabricated housing industry because known steel door frames cannot be adapted for installation in assembly line fashion. The industry demands that the door frame assembly be able to slide quickly into place in the housing unit with both doors pre-hung.
What is needed therefore, is a door frame assembly of simple manufacture for use in the prefabricated housing industry. The door frame assembly should provide superior strength and security while being easy to assemble with reasonable costs. It is essential that the door frame assembly be able to slide into place into a prefabricated housing unit as the unit is progressing on the assembly line.